Background Information

Definition: 

Dynamics are musical instructions notated on a musical piece in order to instruct the musician on which volume to play the music. These instructions are often seen as abbreviations of certain Italian words or symbols on a piece of music, above certain phrases or notes.

History:

Dynamics were not actually used until the late 18th century, although there were some composers who used them earlier. Dynamics were not necessarily needed, beforehand, as a lot of instruments at the time only had two volumes, loud and soft.